#pragma once

#include <iostream>
#include <semaphore.h>

#include <vector>

const static int defaultcap = 5;

template <class T>
class RingQueue
{
public:
    void P(sem_t &sem)
    {
        sem_wait(&sem);
    }
    void V(sem_t &sem)
    {
        sem_post(&sem);
    }

    void Lock(pthread_mutex_t &mutex)
    {
        pthread_mutex_lock(&mutex);
    }

    void UnLock(pthread_mutex_t &mutex)
    {
        pthread_mutex_unlock(&mutex);
    }

    RingQueue(int cap = defaultcap)
        :cap_(cap),ringqueue_(cap),c_step_(0),p_step_(0)
    {
        sem_init(&cdata_sem_,0,0);
        sem_init(&pspace_sem_,0,cap);

        pthread_mutex_init(&c_mutex_,nullptr);
        pthread_mutex_init(&p_mutex_,nullptr);
    }

    void Push(const T& in)  //生产
    {
        P(pspace_sem_);

        Lock(p_mutex_);
        ringqueue_[p_step_] = in;
        //位置后移, 维持环形特征
        p_step_++;
        p_step_ %= cap_;
        UnLock(p_mutex_);

        V(cdata_sem_);

    
    }

    void Pop(T* out)    //消费
    {
        P(cdata_sem_);

        Lock(c_mutex_);
        *out =  ringqueue_[c_step_];
        //位置后移, 维持环形特征
        c_step_++;
        c_step_ %= cap_;
        UnLock(c_mutex_);


        V(pspace_sem_);

    }

    ~RingQueue()
    {
        sem_destroy(&cdata_sem_);
        sem_destroy(&pspace_sem_);

        pthread_mutex_destroy(&c_mutex_);
        pthread_mutex_destroy(&p_mutex_);
        
    }
private:
    std::vector<T> ringqueue_;
    int cap_;

    int c_step_;    //消费者下标
    int p_step_;    //生产者下标

    sem_t cdata_sem_;   //消费者关注的数据资源
    sem_t pspace_sem_;  //生产者关注的空间资源

    pthread_mutex_t c_mutex_;
    pthread_mutex_t p_mutex_;
};